This invention relates to internal combustion engines having variable compression ratio mechanisms incorporated therein.
The compression ratio of an internal combustion engine is one design factor that impacts the thermal efficiency of the engine. Under ideal conditions, the thermal efficiency increases as the compression ratio increases. However, with spark ignition engines, the maximum levels of compression ratio that can be utilized are limited by engine knock.
Engine knock is most likely to occur at higher loads where the cylinder pressures are at their highest. These high loads therefore limit the amount of compression ratio or the compression ratio levels that are usable within an engine. With a constant compression ratio, this, of course, limits the efficiency that can be achieved at lower loads where without restriction the higher compression ratios could be utilized.
It is an object of this invention to provide an improved connecting rod for use in an internal combustion engine.
In one aspect of the invention, the connecting rod has a small end which is adapted to connect with a piston and a large end which is adapted to connect with a crankshaft, and an intermediate section in which a spring member is employed.
In another aspect of the present invention, the spring member permits the smaller section to be displaced toward the larger section when loads on the piston are increased above a predetermined value.
In another aspect of the present invention, a pin member joins the opposite smaller and larger sections and the spring member is circumjacent the pin member and imposes a separating load between the smaller and larger sections.
In a further aspect of the present invention, the smaller connecting rod section and the larger connecting rod section are joined by a sleeve member surrounding the outer periphery thereof and are operatively connected by spring members disposed within the sleeve immediate the small connecting rod section and the large connecting rod section.
In yet a further aspect of the present invention, the spring member provides a lost motion connection between the ends of the connecting rod.